Pep band

A pep band is an ensemble of instrumentalists who play at functions or events with the purpose of entertaining and "pepping" up a crowd. Often members of a pep band are a subset of people from a larger ensemble such as a marching band or a concert band. Pep bands are generally associated with performing at pep rallies and sporting events (usually football, basketball or hockey). With a few exceptions, pep bands are exclusive to the collegiate and high school level. The typical instrumentation of a pep band is the same as most marching bands, using mainly woodwind, brass, and percussion instruments. Pep bands typically don't use primarily orchestral instruments (double reeds, strings, etc.), but this is not a hard set limitation.

Pep bands have been in existence for a very long time, however their origins are vague and hard to find. The concept of pep band most likely sprung from marching band (a band during sporting events with choreography while they play music, normally with uniforms). While playing at competitive events, should both teams have a pep band, the bands will compete and go back and forth playing songs. Although pep bands mainly play modern pop music, other styles will occasionally be incorporated such as jazz.

...
Wikipedia